diff options
Diffstat (limited to 'usr.bin/write')
| -rw-r--r-- | usr.bin/write/Makefile | 5 | ||||
| -rw-r--r-- | usr.bin/write/Makefile.depend | 17 | ||||
| -rw-r--r-- | usr.bin/write/write.1 | 106 | ||||
| -rw-r--r-- | usr.bin/write/write.c | 344 |
4 files changed, 472 insertions, 0 deletions
diff --git a/usr.bin/write/Makefile b/usr.bin/write/Makefile new file mode 100644 index 000000000000..d7e362cc9c8f --- /dev/null +++ b/usr.bin/write/Makefile @@ -0,0 +1,5 @@ +PROG= write +BINMODE=2555 +BINGRP= tty + +.include <bsd.prog.mk> diff --git a/usr.bin/write/Makefile.depend b/usr.bin/write/Makefile.depend new file mode 100644 index 000000000000..38d979787478 --- /dev/null +++ b/usr.bin/write/Makefile.depend @@ -0,0 +1,17 @@ +# Autogenerated - do NOT edit! + +DIRDEPS = \ + include \ + include/xlocale \ + lib/${CSU_DIR} \ + lib/libc \ + lib/libcapsicum \ + lib/libcasper/libcasper \ + lib/libcompiler_rt \ + + +.include <dirdeps.mk> + +.if ${DEP_RELDIR} == ${_DEP_RELDIR} +# local dependencies - needed for -jN in clean tree +.endif diff --git a/usr.bin/write/write.1 b/usr.bin/write/write.1 new file mode 100644 index 000000000000..d94957a2e777 --- /dev/null +++ b/usr.bin/write/write.1 @@ -0,0 +1,106 @@ +.\" Copyright (c) 1989, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" This code is derived from software contributed to Berkeley by +.\" Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.Dd February 13, 2012 +.Dt WRITE 1 +.Os +.Sh NAME +.Nm write +.Nd send a message to another user +.Sh SYNOPSIS +.Nm +.Ar user +.Op Ar tty +.Sh DESCRIPTION +The +.Nm +utility allows you to communicate with other users, by copying lines from +your terminal to theirs. +.Pp +When you run the +.Nm +command, the user you are writing to gets a message of the form: +.Pp +.Dl Message from yourname@yourhost on yourtty at hh:mm ... +.Pp +Any further lines you enter will be copied to the specified user's +terminal. +If the other user wants to reply, they must run +.Nm +as well. +.Pp +When you are done, type an end-of-file or interrupt character. +The other user will see the message +.Ql EOF +indicating that the +conversation is over. +.Pp +You can prevent people (other than the super-user) from writing to you +with the +.Xr mesg 1 +command. +.Pp +If the user you want to write to is logged in on more than one terminal, +you can specify which terminal to write to by specifying the terminal +name as the second operand to the +.Nm +command. +Alternatively, you can let +.Nm +select one of the terminals \- it will pick the one with the shortest +idle time. +This is so that if the user is logged in at work and also dialed up from +home, the message will go to the right place. +.Pp +The traditional protocol for writing to someone is that the string +.Ql \-o , +either at the end of a line or on a line by itself, means that it is the +other person's turn to talk. +The string +.Ql oo +means that the person believes the conversation to be +over. +.Sh SEE ALSO +.Xr mesg 1 , +.Xr talk 1 , +.Xr wall 1 , +.Xr who 1 +.Sh HISTORY +A +.Nm +command appeared in +.At v1 . +.Sh BUGS +The sender's +.Ev LC_CTYPE +setting is used to determine which characters are safe to write to a +terminal, not the receiver's (which +.Nm +has no way of knowing). diff --git a/usr.bin/write/write.c b/usr.bin/write/write.c new file mode 100644 index 000000000000..cbdc34ec0f4f --- /dev/null +++ b/usr.bin/write/write.c @@ -0,0 +1,344 @@ +/*- + * SPDX-License-Identifier: BSD-3-Clause + * + * Copyright (c) 1989, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <sys/param.h> +#include <sys/capsicum.h> +#include <sys/filio.h> +#include <sys/signal.h> +#include <sys/stat.h> +#include <sys/time.h> + +#include <capsicum_helpers.h> +#include <ctype.h> +#include <err.h> +#include <errno.h> +#include <locale.h> +#include <paths.h> +#include <pwd.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <utmpx.h> +#include <wchar.h> +#include <wctype.h> + +void done(int); +void do_write(int, char *, char *, const char *); +static void usage(void) __dead2; +int term_chk(int, char *, int *, time_t *, int); +void wr_fputs(wchar_t *s); +void search_utmp(int, char *, char *, char *, uid_t); +int utmp_chk(char *, char *); + +int +main(int argc, char **argv) +{ + unsigned long cmds[] = { TIOCGETA, TIOCGWINSZ, FIODGNAME }; + cap_rights_t rights; + struct passwd *pwd; + time_t atime; + uid_t myuid; + int msgsok, myttyfd; + char tty[MAXPATHLEN], *mytty; + const char *login; + int devfd; + + (void)setlocale(LC_CTYPE, ""); + + devfd = open(_PATH_DEV, O_RDONLY); + if (devfd < 0) + err(1, "open(/dev)"); + cap_rights_init(&rights, CAP_FCNTL, CAP_FSTAT, CAP_IOCTL, CAP_LOOKUP, + CAP_PWRITE); + if (caph_rights_limit(devfd, &rights) < 0) + err(1, "can't limit devfd rights"); + + /* + * Can't use capsicum helpers here because we need the additional + * FIODGNAME ioctl. + */ + cap_rights_init(&rights, CAP_FCNTL, CAP_FSTAT, CAP_IOCTL, CAP_READ, + CAP_WRITE); + if (caph_rights_limit(STDIN_FILENO, &rights) < 0 || + caph_rights_limit(STDOUT_FILENO, &rights) < 0 || + caph_rights_limit(STDERR_FILENO, &rights) < 0 || + caph_ioctls_limit(STDIN_FILENO, cmds, nitems(cmds)) < 0 || + caph_ioctls_limit(STDOUT_FILENO, cmds, nitems(cmds)) < 0 || + caph_ioctls_limit(STDERR_FILENO, cmds, nitems(cmds)) < 0 || + caph_fcntls_limit(STDIN_FILENO, CAP_FCNTL_GETFL) < 0 || + caph_fcntls_limit(STDOUT_FILENO, CAP_FCNTL_GETFL) < 0 || + caph_fcntls_limit(STDERR_FILENO, CAP_FCNTL_GETFL) < 0) + err(1, "can't limit stdio rights"); + + caph_cache_catpages(); + caph_cache_tzdata(); + + /* + * Cache UTX database fds. + */ + setutxent(); + + /* + * Determine our login name before we reopen() stdout + * and before entering capability sandbox. + */ + myuid = getuid(); + if ((login = getlogin()) == NULL) { + if ((pwd = getpwuid(myuid))) + login = pwd->pw_name; + else + login = "???"; + } + + if (caph_enter() < 0) + err(1, "cap_enter"); + + while (getopt(argc, argv, "") != -1) + usage(); + argc -= optind; + argv += optind; + + /* check that sender has write enabled */ + if (isatty(fileno(stdin))) + myttyfd = fileno(stdin); + else if (isatty(fileno(stdout))) + myttyfd = fileno(stdout); + else if (isatty(fileno(stderr))) + myttyfd = fileno(stderr); + else + errx(1, "can't find your tty"); + if (!(mytty = ttyname(myttyfd))) + errx(1, "can't find your tty's name"); + if (!strncmp(mytty, _PATH_DEV, strlen(_PATH_DEV))) + mytty += strlen(_PATH_DEV); + if (term_chk(devfd, mytty, &msgsok, &atime, 1)) + exit(1); + if (!msgsok) + errx(1, "you have write permission turned off"); + + /* check args */ + switch (argc) { + case 1: + search_utmp(devfd, argv[0], tty, mytty, myuid); + do_write(devfd, tty, mytty, login); + break; + case 2: + if (!strncmp(argv[1], _PATH_DEV, strlen(_PATH_DEV))) + argv[1] += strlen(_PATH_DEV); + if (utmp_chk(argv[0], argv[1])) + errx(1, "%s is not logged in on %s", argv[0], argv[1]); + if (term_chk(devfd, argv[1], &msgsok, &atime, 1)) + exit(1); + if (myuid && !msgsok) + errx(1, "%s has messages disabled on %s", argv[0], argv[1]); + do_write(devfd, argv[1], mytty, login); + break; + default: + usage(); + } + done(0); + return (0); +} + +static void +usage(void) +{ + (void)fprintf(stderr, "usage: write user [tty]\n"); + exit(1); +} + +/* + * utmp_chk - checks that the given user is actually logged in on + * the given tty + */ +int +utmp_chk(char *user, char *tty) +{ + struct utmpx lu, *u; + + strncpy(lu.ut_line, tty, sizeof lu.ut_line); + while ((u = getutxline(&lu)) != NULL) + if (u->ut_type == USER_PROCESS && + strcmp(user, u->ut_user) == 0) { + endutxent(); + return(0); + } + endutxent(); + return(1); +} + +/* + * search_utmp - search utmp for the "best" terminal to write to + * + * Ignores terminals with messages disabled, and of the rest, returns + * the one with the most recent access time. Returns as value the number + * of the user's terminals with messages enabled, or -1 if the user is + * not logged in at all. + * + * Special case for writing to yourself - ignore the terminal you're + * writing from, unless that's the only terminal with messages enabled. + */ +void +search_utmp(int devfd, char *user, char *tty, char *mytty, uid_t myuid) +{ + struct utmpx *u; + time_t bestatime, atime; + int nloggedttys, nttys, msgsok, user_is_me; + + nloggedttys = nttys = 0; + bestatime = 0; + user_is_me = 0; + + while ((u = getutxent()) != NULL) + if (u->ut_type == USER_PROCESS && + strcmp(user, u->ut_user) == 0) { + ++nloggedttys; + if (term_chk(devfd, u->ut_line, &msgsok, &atime, 0)) + continue; /* bad term? skip */ + if (myuid && !msgsok) + continue; /* skip ttys with msgs off */ + if (strcmp(u->ut_line, mytty) == 0) { + user_is_me = 1; + continue; /* don't write to yourself */ + } + ++nttys; + if (atime > bestatime) { + bestatime = atime; + (void)strlcpy(tty, u->ut_line, MAXPATHLEN); + } + } + endutxent(); + + if (nloggedttys == 0) + errx(1, "%s is not logged in", user); + if (nttys == 0) { + if (user_is_me) { /* ok, so write to yourself! */ + (void)strlcpy(tty, mytty, MAXPATHLEN); + return; + } + errx(1, "%s has messages disabled", user); + } else if (nttys > 1) { + warnx("%s is logged in more than once; writing to %s", user, tty); + } +} + +/* + * term_chk - check that a terminal exists, and get the message bit + * and the access time + */ +int +term_chk(int devfd, char *tty, int *msgsokP, time_t *atimeP, int showerror) +{ + struct stat s; + + if (fstatat(devfd, tty, &s, 0) < 0) { + if (showerror) + warn("%s%s", _PATH_DEV, tty); + return(1); + } + *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */ + *atimeP = s.st_atime; + return(0); +} + +/* + * do_write - actually make the connection + */ +void +do_write(int devfd, char *tty, char *mytty, const char *login) +{ + char *nows; + time_t now; + char host[MAXHOSTNAMELEN]; + wchar_t line[512]; + int fd; + + fd = openat(devfd, tty, O_WRONLY); + if (fd < 0) + err(1, "openat(%s%s)", _PATH_DEV, tty); + fclose(stdout); + stdout = fdopen(fd, "w"); + if (stdout == NULL) + err(1, "%s%s", _PATH_DEV, tty); + + (void)signal(SIGINT, done); + (void)signal(SIGHUP, done); + + /* print greeting */ + if (gethostname(host, sizeof(host)) < 0) + (void)strcpy(host, "???"); + now = time((time_t *)NULL); + nows = ctime(&now); + nows[16] = '\0'; + (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n", + login, host, mytty, nows + 11); + + while (fgetws(line, sizeof(line)/sizeof(wchar_t), stdin) != NULL) + wr_fputs(line); +} + +/* + * done - cleanup and exit + */ +void +done(int n __unused) +{ + (void)printf("EOF\r\n"); + exit(0); +} + +/* + * wr_fputs - like fputs(), but makes control characters visible and + * turns \n into \r\n + */ +void +wr_fputs(wchar_t *s) +{ + +#define PUTC(c) if (putwchar(c) == WEOF) err(1, NULL); + + for (; *s != L'\0'; ++s) { + if (*s == L'\n') { + PUTC(L'\r'); + PUTC(L'\n'); + } else if (iswprint(*s) || iswspace(*s)) { + PUTC(*s); + } else { + wprintf(L"<0x%X>", *s); + } + } + return; +#undef PUTC +} |